Surface treatment is an additional process to increase the anti-rust and wear-resistant functions of the material surface or to improve the decoration to enhance its appearance.
The painting of automobile bodies, the printing of manufacturer's name and other information on the surface of home appliances, and the "electroplating" under the paint of guardrails are all typical examples of surface treatment.
Heat treatments applied to metal parts such as gears and blades, such as quenching, are also classified as surface treatments.
Surface preparation can be broadly divided into removal processes, such as scratching or melting the surface, and additive processes, such as painting that adds something else to the surface.